Subnet Mask Description

Subnet Mask

The human can tell the difference that which are the network bits and the host bits in an IP address but to make the computer understand the network bits and the host bits we use the subnet mask.

A Subnet mask is a 32-bit value which is used to create a boundary between network portion and the host portion. Computers that belong to a subnet are being addressed by the same, identical  and significant IP address.

In Networking subnet, the representation is shown by

1-------> Network

0-------> Host

Subnet mask according to Classes

N is for network 

H is for Host

w.x.y.z represents the IP address
   
For Class A

   N       H   

  w.     x.y.z

 255.    0.0.0 

There is one Network bit and three host bits in Class A 

                                             

 For Class B

   N              H   

w.x.             y.z

255.255.     0.0

There are two Network bits and two host bits in Class B

                                          

For Class C

   N                   H   

w.x.y                .z

255.255.255.    0

                                          

There are three Network bits and one host bit in Class C 

 Methods to Repesent Subnet mask

Dotted Decimal Notation              BIT Count

255 . 0 . 0 . 0                                       8

255 . 255 . 0 . 0                                  16

255 . 255 . 255 . 0                              32

We all know that one bit of an IP address is equal to 8 so this is another way to count the bit in a subnet mask.

So this is how we write an IP address with a subnet mask.

10.0.0.1/8

187.4.5.3/16

215.3.5.23/32

Note:this is just the basic concept of subnet, there will mathematical conversion also which will be discussed in the later post.